Joe, I think 1 o'clock (instead of 12 o'clock) might still be OK and/or typical? Maybe some other 5370A users can tell us where their Trigger Level pots are pointing when centered for triggering on a weak signal. (The pots point to 12 o'clock on my 5370B, but I can't remember exactly where they might point on a typical "A".)
I do know that some of the 5370A A3/A4 Input Amp & Schmitt Trigger I.C.s developed "I.C. rot" many years after manufacture (due to a contamination problem during manufacture). For units so afflicted, the symptom was that "Preset" trigger level was no longer correct, but the trigger level could still be successfully set manually. For these cases, as the years progressed (and the "rot" worsened), you had to turn the manual trigger level pot further and further to one direction to find trigger. As the years of deterioration continued, there came a point where both trigger level setability and sensitivity were no longer acceptable. If you have only a small trigger level issue in "Preset" mode, my thinking is that you can still correct for it by doing the A3/A4 input adjustments. Best, Greg ----- Original Message ----- From: "Joseph Gray" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, October 10, 2009 2:23 PM Subject: Re: [time-nuts] 5370A Greg, Yes, the trigger levels are near zero when the LEDs are flashing. The level pots are both at 1 o'clock, instead of 12 o'clock, however. There does seem to be a problem with the preset trigger postition. Although the display shows 0.00V when at preset, I don't think it is. When I manually set the levels to 0.00V, the TI shows 100nS. At preset levels, the TI is noticeably higher. Joe Gray KA5ZEC _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
